Intraoral Scanners and Printing Models

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A recent survey concluded that 39% of dentists will be purchasing intraoral scanners (IOS) within the next three years. If this is correct, the need for digital model manufacturing will skyrocket. Today, there are just two possible manufacturing choices: milling or 3D printing. After looking at an ROI on milling models I have determined milling in quantity lacks economic viability. However, milling 3-5 cases a week, if your mill(s) have capacity, works fine.

3D Printing — From R&D to Mainstream Manufacturing

When 3D printing was first introduced, it was embraced as a faster, less expensive way for manufacturers to obtain prototype parts while undergoing new product development. At this time 3D printing was a breakthrough technology that reduced cost and time. More recently, 3D printing has found a path into mainstream manufacturing. For dentistry, there are just a small number of companies manufacturing 3D printers. One of which, Stratasys, has multiple machines offered at different price points, accuracy, and functionality. The primary dental products currently being produced with Stratasys printers are models for ortho, C&B and implants, clear surgical guides, and custom trays. In the near future we will probably have access to printed dentures, and further out, final composite restorations and possibly printed ceramics.

Finding the Intersection of Acceptable Accuracy, Output, And Price

Back to digital impressions and model manufacturing. When printing models there are a few considerations. These include accuracy, output, and cost. The accuracy of some printers for printed models is now adequate to obtain clinically acceptable crown and bridge restorations. Printer resolution is an important consideration to determine accuracy. For a start, it’s good to know how many microns of material are printed per curing cycle. Models are generally built in a series of layers starting at the base and building towards the occlusal surfaces. For crown and bridge these layers should be 20 microns or less. In addition, don’t be fooled, not all printers that print in 20 micron layers are highly accurate. Printers also come in different sizes, print at different speeds, and have a wide range of prices.

A Familiar Workflow

For 3D printing at CAP we are currently running the Stratasys Objet30 OrthoDesk for surgical guides and the Objet Eden260VS for crown and bridge and implant model fabrication. The workflow is not that dissimilar to milling. First, we load the IOS scans into 3Shape Model Builder software. This software is setup to accept scans from any IOS device that outputs an STL file. Then margins are marked and models are trimmed virtually. Once a batch of models has gone through the Model Builder software, CAM is performed, which is similar to putting crowns in a disc. The printer is kicked off and prints 12-20 cases depending on the size of the models. Once printed, the models are soaked in a solution of lye and finally cleaned in a high water pressure unit. Dies are sorted, digital analogs are inserted in implant models, and the models are off for restoration fabrication.

A New 3D Printer with an Automated Application

A more recent development from Stratasys, the Objet260 Dental Selection printer. This high-end solution has the required accuracy and prints up to three different materials simultaneously. That said, we can now reduce implant modes with a cut back soft tissue section and a pink soft tissue part that fits the printed model. I love this automated application and can’t wait to get this printer at CAP.

When evaluating model cost using the Eden260VS, the material cost for producing a quadrant set of models is about $7. Full arch set is about $12. For labs that are embracing the digital workflow, the combination of the Eden260VS and 3Shape Model Builder software fills the niche nicely.

As usual, thanks for reading,

Bob Cohen, CDT

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